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BBC Research and Development Reports

A collection of BBC Research and Development reports and white papers, dating from the 1960s through to 1996.



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R&D Report 1972-33 : Transmitting aerial distribution transformers and hybrids for use at low-powerUHF relay stations G.H. Millard The design and performance are given of four printed circuit distribution transformers and 3 dB directional coupler all for use with printed panel aerials at low-power UHF relay stations.
Topics: transformer, transformers, relay, coupler, bbc, uhf, hybrid, impedance, distribution, aerial, relay...
R&D Report 1980-03 : Digital sound: an investigation of delta-modulation/pulse-code-modulation analogue-to-digital conversion. R.A. Belcher, W.I. Manson, T.A. Moore The BBC has used pulse-code modulation (PCM) techniques for sound programme distribution since 1972. The established 13-channel system employs linearly-coded samples which are quantised to 13-bit accuracy. However, a second generation system now being developed will require an initial coding of samples to 14-bit accuracy;...
Topics: integrator, digital, modulation, signal, converter, frequency, dither, noise, bbc, delta, delta...
R&D Report 1959-08 : Low-signal amplifying valves for use at U.H.F. R.G. Manton The object of this report is to review some of the types of valve that are suitable for use in u.h.f. amplifying stages in receivers, and to describe units which have been constructed to test the performance of two of these valves at a frequency of about 655 Mc/s.
Topics: amplifier, valve, output, input, amplifiers, anode, bandwidth, grid, gain, impedance, electrical...
R&D Report 1986-13 : VHF-FM radio broadcasting: tests to compare horizontal, vertical and mixed polarisations. G.H. Taylor, D.S. Cox The BBC is re-engineering its VHF-FM radio networks from horizontal to mixed polarization. This Report describes tests carried out to monitor this change and which confirm the advantages of mixed polarization. Tests from the BBC transmitting station at Wenvoe to compare vertical and horizontal polarization are described. It is concluded that mixed polarization...
Topics: antenna, multipath, polarized, receiving, wrotham, signal, antennas, polarization, reception,...
R&D Report 1973-05 : Ionospheric non-linearity: Protection ratios required against cross-modulation interference (Luxembourg Effect) D.J. Whythe, C.R.G. Reed Studies of intermodulation of a weak signal by a strong signal in the ionosphere have defined the degree to which the level of intermodulation varies as a function of modulation frequency of the strong signal. This report describes experiments which show that, as a result, a 6 dB relaxation, relative to co-channel interference, may be...
Topics: modulation, ionospheric, interference, bbc, ionosphere, frequency, signal, interfering, capacitor,...
R&D Report 1971-44 : Digital line-store standards conversion: a feasability study R. Walker The present analogue line-store converters which convert video signals from the 625/50 standard to the 405/50 standard required for the VHF transmissions have been in service for several years. Some of the converters will reach the end of their service lives before 405-line transmissions are terminated and will need to be replaced. It was considered worthwhile to investigate the feasibility of a new...
Topics: clock, output, pulse, pulses, storage, trigger, interpolation, input, frequency, digital,...
R&D Report 1970-09 : UHF television: the interference caused by a receiver operating on channel n to an adjacent receiver tuned to n+4 J.G. Spencer The interference that a television receiver tuned to a UHF channel n can cause to a neighbouring receiver tuned to channel n + 4 was considered in the early stages of development of the UHF plan. It then appeared that this type of interference could constitute a serious impairment of the quality of a colour television service at UHF. Since that...
Topics: receiver, interference, aerial, mhz, receivers, channel, coupling, frequency, strength, tuned,...
R&D Report 1973-38 : Holography: A general survey E.W. Taylor The history of the development of holography is surveyed and an introduction to the general theory is given. Techniques for the preparation of holograms are described, and materials for use as holographic recording media are discussed. An extensive list of references is included.
Topics: holographic, hologram, beam, interference, image, photographic, radiation, object, light,...
R&D Report 1984-20 : Digital standards conversion: interpolation theory and aperture synthesis. C.K.P. Clarke, N.E. Tanton A frequency domain approach is used to investigate digital interpolation for standards conversion. To illustrate the background theory, one-dimensional sampling and interpolation is described in general terms, including methods for synthesising interpolation apertures and the effects of aperture quantisation. With the two-dimensional vertical-temporal sampling of...
Topics: vertical, temporal, frequency, aperture, components, spectrum, characteristic, interpolation,...
R&D Report 1962-37 : Symposium of electromagnetic theory and antennas, Copenhagen, 25th - 30th June 1962 H. Page, P. Knight A report on the Symposium on Electromagnetic Theory and Antennas held in Copenhagen 25-30 June 1962. A total of 140 papers were presented, covering various areas of Electromagnetic and Antenna theory. In this report it is therefore proposed to indicate only the broad trends of current research, with more detailed reference to those papers directly related to...
Topics: aerials, propagation, radiation, waveguides, arrays, electromagnetic, anisotropic, aerial,...
R&D Report 1994-13 : DRACULA: Dynamic range control for broadcasting and other applications. N.H.C. Gilchrist The BBC has developed a digital processor which is capable of reducing the dynamic range of audio in an unobtrusive manner. It is ideally suited to the task of controlling the level of musical programmes. Operating as a self-contained dynamic range controller, the processor is suitable for controlling levels in conventional AM or FM broadcasting, or for applications such as the...
Topics: dynamic, gain, range, digital, signal, controller, compression, audio, processor, broadcasting,...
R&D Report 1991-08 : VHF (Band II) propagation tests across the Irish Sea. J. Middleton Measurements of Band II transmissions across the Irish Sea over a 13-month period between 1983 and 1984 have been analysed and compared with prediction methods normally used to calculate interference from broadcast transmissions (BBC and CCIR methods). They were also compared with North Sea measurements made in 1954. The measurements show that both methods predict interference levels which are not...
Topics: bbc, measurements, ccir, strength, propagation, antenna, field, transmitter, sea, height, antenna...
R&D Report 1967-10 : Test card 53: a test card for checking the spectral sensitivity of image orthicon camera tubes H.A.S. Philippart It has been apparent for some time that a simple and accurate test card is required to test the spectral response of image orthicon camera tubes, and Test Card 53 was devised for this purpose. It consists of six narrow band-pass dielectric filters with peak wavelengths located within the visible spectrum, and two reference filters set to +/- 10% of the...
Topics: spectral, filters, test, camera, response, orthicon, tube, filter, test card, reference, spectral...
R&D Report 1990-01: Antennas for portable VHF-FM receivers. R.D.C. Thoday This report describes a number of compact antennas which have been considered as replacements for the standard whip antenna which is normally fitted to VHF portable receivers. A comparison made of their characteristics shows that, of the antennas considered in the survey, the quarter whip still provides the best sensitivity. However the normal-mode helix is a more convenient and compact antenna and is shown to perform...
Topics: antenna, receiver, helix, whip, sensitivity, tuning, ferrite, antennas, impedance, portable,...
R&D Report 1986-18 : LF and MF sky-wave propagation: a comparison of measurements made at sunset and sunrise P. Knight, W.F. Williams The strength of LF and MF sky-wave signals is greatest at night and weakest during the day. The increase in field-strength which occurs at sunset has been extensively studied but less is known about the decrease which occurs at sunrise. This Report describes a series of measurements made by members of the European Broadcasting Union (EBU) which covers both...
Topics: measurements, sunrise, sunset, field, strength, seasonal, curve, ccir, khz, curves, ccir diurnal,...
R&D Report 1994-12 : A wideband absorber for television studios. M.D.M. Baird The acoustic treatment in BBC television studios has taken various forms to date, all of which have been relatively expensive, some of which provide inadequate absorption. An investigation has been conducted into the possibilities of producing a new type of wideband absorber which, would be more economic, also taking installation time into account, than earlier designs. This Report describes the absorption...
Topics: absorption, absorber, wideband, frequency, acoustic, mineral, bbc, zintec, weldmesh, absorbers,...
R&D Report 1994-14 : The sound insulations of studio doors: Part 1: Door Blanks G.D. Plumb, R. Clark The sound insulations of a range of different door blanks were measured. The results were compared with the sound insulations of existing BBC door blanks. The new doors were made from medium density fibreboard (MDF) which is more stable than the blockboard used in existing studio doors. Consequently, they should require less maintenance and adjustment and should have a longer lifespan. The...
Topics: mdf, door, insulations, bitumen, damping, measured, bbc, sound, acoustic, lightweight, band centre,...
R&D Report 1989-05 : Satellite broadcasting: requirements for the receiving antenna. J.H. Stott The receiving antenna plays a significant part in the reception of television signals broadcast from a satellite in so-called Direct Broadcasting by Satellite (DBS). The performance of the antenna must be sufficiently good to ensure that signals are received without suffering adverse effects of noise or interference. A hypothetical receiver specification was used during the planning of satellite...
Topics: antenna, interference, attenuation, receiver, satellite, temperature, dbs, noise, bbc, receiving,...
R&D Report 1973-06 : Equipment for the transfer of digital video signals to paper tape C.K.P Clarke A digital computer can be used to simulate processing methods for the bit-rate reduction of digital television. To assess such methods, television signals must be converted to a form compatible with computer data-handling systems. This report describes equipment for transferring monochrome pulse-code modulation signals derived from a slide scanner to punched paper tape. One eight-bit word is...
Topics: signals, picture, digital, counter, sampling, samples, punched, bbc, paper, transfer, slide...
R&D Report 1954-34 : A new photo-electric optical bench. W.N. Sproson An outline of the photoelectric method of testing lenses is given, together with some details of the two types of test pattern now in use and the form of aperture correction necessitated by the finite width of the scanning slit. The photoelectric test bench is described and a few preliminary results are quoted.
Topics: lens, modulation, wave, test, bench, microscope, optical, pattern, slit, photoelectric, wave...
R&D Report 1957-04 : The service area of the Pontop Pike television transmitter. D.W. Taplin, D.F. Cooney, I. Rhodes A field strength survey of the Pontop Pike television transmission has been carried out. The service provided conforms well with that expected from site test measurements. The heavily populated industrial areas of Tyneside area well served. The Tees-side area is provided with a fair service.
Topics: pontop, pike, transmitter, transmission, strength, contours, field, median, pontop pike, populated,...
R&D Report 1963-27 : An introduction to the theory of aerials H. Page This report gives an introduction to the theory of aerials with emphasis on broadcasting. The function of an aerial, when transmitting, is to propagate the electro-magnetic waves flowing from the source into space.
Topics: aerial, radiation, impedance, vertical, doublet, field, aerials, current, transmitting, pattern,...
R&D Report 1959-21 : Visit to the Florida terminal of the A.T. and T. Co. trapospheric scatter communications link to Cuba R.A. Rowden A report on a visit to Florida Terminal of the A.T. and T. Co. Troposheric Scatter Communications link to Cuba.
Topics: link, scatter, florida, television, tropospheric, median, multichannel, transmission, terminal,...
R&D Report 1967-35 : Kidderminster UHF relay station: Summary of installation G.H. Millard A brief data sheet detailing frequencies, equipment installed, radiation characteristics etc, including graphs of radiation patterns.
Topics: kidderminster, unwanted, mhz, vertical, ith, transmitter, radiation, iii, stockholm, relay
R&D Report 1965-36 : Statistical survey of scanning amplitudes and aspect ratio of domestic television receivers R.F. Vigurs Measurements have been made on a number of domestic television receivers, operating under normal home conditions, with regard to their settings of horizontal and vertical scanning amplitudes and aspect ratio. These measurements revealed that the accuracies of the adjustments made on installation, and the standard maintained by the receivers, in these respects, were...
Topics: picture, visible, aspect, receivers, distributions, histograms, statistical, width, ratio, height,...
R&D Report 1977-11 : A Band II ferrite aerial unit for portable receivers. R.D.C. Thoday The whip aerial needed for good reception at VHF is a drawback to the use of portable sound receivers. A small VHF aerial unit has been built using a recently developed ferrite rod which is commercially available at low cost. The unit has been incorporated inside the cabinet of a simple VHF domestic portable receiver. It provides adequate signal pick-up and has the advantage of being less disturbed by...
Topics: ferrite, aerial, receiver, rod, portable, signal, circuit, unit, tuned, tuning, maximum signal,...
R&D Report 1981-04 : VHF radio-data: experimental BBC transmissions. S.R. Ely This report describes in detail a new system for transmitting data signals from vhf radio-broadcast transmitters along with the normal sound-programme signal. These data signals are primarily intended to aid radio listeners in tuning their receivers to a desired station or programme. These data signals are primarily intended to aid radio listeners in tuning their receivers to a desired station or programme. They...
Topics: block, data, synchronisation, code, crc, khz, transmitted, subcarrier, bbc, decoder, biphase...
BBC Research and Development Reports
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R&D Report 1954-29 : The design of the LIP microphone Type L2. H.D. Harwood, R.J. Packer, R.A. Ticehurst A new lip microphone of the "noise-cancelling" type has been developed, having properties basically similar to those of the type L1 but incorporating a number of improvements. The problems peculiar to this type of instrument are analysed and the construction, performance and special features of the new design are described. A large number of production models has given...
Topics: microphone, type, frequency, ribbon, magnetic, breath, noise, response, acoustic, ambient, breath...
R&D Report 1961-07 : Crystal-diode modulators for the frequency range 10-1000 Mc/s. G.J. Phillips, R.G. Manton This report describes the development of low-power balanced diode modulators suitable for amplitude modulation by television or sound signals of a carrier in the frequency range 10-1000 Mc/s. From an original model, built in 1954, two later models have been developed having better performance in regard to the insertion loss at the carrier frequency, and uniformity of modulation...
Topics: modulator, modulation, frequency, insertion, signal, amplitude, impedance, transformer, output,...
R&D Report 1960-12 : The Service area of the Sandale television transmitter. D.W. Taplin, C.J. White, F.P. Raine This report gives the results of a field strength survey of the Sandale television transmitter. It is shown that the service area conforms well with that predicted from site test measurements, although there are some small towns in which the field strength is considerably less than the value predicted.
Topics: sandale, strength, field, towns, contours, polarization, television, transmitter, field strength,...
R&D Report 1961-16 : Visit to Jersey and Normandy to investigate co-channel interference between North Hessary Tor and Caen. R.F. Vigurs An investigation has been carried out in Jersey and parts of the Cherbourg peninsula to enquire into complaints that television reception in the service area of the French transmitting station near Caen was being affected by interference from the B.B.C. transmitter at North Hessary Tor. A few days were spent in discussion and carrying out observations. As...
Topics: frequency, interference, hessary, tor, transmitter, french, north, caen, television, receiver,...
R&D Report 1968-34 : Lochgilphead VHF relay station: Summary of installation R.D.C. Thoday, J.P. Crean Brief data sheet detailing equipment used, frequencies, radiation characteristics etc, together with a graph of horizontal radiation.
Topics: band, aerial, lochgilphead, horizontal, installation, radiation, pid, transmitting, bbc,...
R&D Report 1968-18 : U.H.F. relay station aerials inside 914 mm diameter glass-fibre cylinders J.L. Eaton, A.D. Olver The BBC aerial for UHF relay stations was designed for operation inside a glass-fibre cylinder of 387 mm diameter. More recently a new requirement has arisen to house the aerial inside a 914 mm diameter cylinder to permit access. An investigation was therefore carried out to study the effect of a 914 mm cylinder on the performance of the aerial. A position of the aerial...
Topics: cylinder, mhz, aerial, dielectric, dipole, spacing, band, diameter, impedance, sin, dielectric...
R&D Report 1967-31 : Lark Stoke UHF relay station: Summary of installation G.H. Millard A brief data sheet detailing frequencies, equipment installed, radiation characteristics etc, including graphs of horizontal and vertical radiation patterns.
Topics: mhz, stoke, lark, radiation, transmitter, relay, power, vertical, installation, technological, lark...
R&D Report 1967-61 : Methods for shaping the vertical radiation patterns of VHF and UHF transmitting aerials P.C.J. Hill An important problem in the design of VHF and UHF transmitting aerials is the provision of a vertical radiation pattern which gives approximately uniform field strength over the prescribed service area. A good solution is provided by a beam-tilted cosecant-shaped radiation pattern. Several methods are described for synthesizing radiation patterns of this type by varying...
Topics: pattern, phase, amplitude, aerial, method, distributions, current, distribution, array, aperture,...
R&D Report 1966-53 : Transmitting aerial for the Bexhill VHF television station D.W. Osborne, R.D.C. Thoday, J.P. Crean The Bexhill relay station came into operation on 21st March 1966. It provides a television service to Bexhill only.
Topics: aerial, transmitting, horizontal, bexhill, reflector, templet, band, dipole, radiation, udc,...
R&D Report 1963-49 : Noise and vibration levels on the South Bank site of the proposed opera house and National Theatre. C.L.S. Gilford. Measurements of airborne noise and ground vibration on the South Bank of the Thames between County Hall and Hungerford Bridge show that the roofs of the proposed National Theatre and Opera House should give a mean sound reduction of 69 dB with a slope not exceeding 7 dB per octave. Protection of the National Theatre from vibration will present considerable...
Topics: vibration, opera, measurements, underground, ground, hungerford, maximum, theatre, national, site,...
R&D Report 1979-25 : Spherical harmonic analysis and some applications to surround sound. P.S. Gaskell Spherical harmonic analysis in three dimensions and azimuthal harmonic analysis in two dimensions are powerful methods for studying the problems associated with transmitting surround sound. This Report describes these methods and shows how they can highlight some of the fundamental factors and limitations of surround sound transmission. A number of specific examples are presented.
Topics: sin, sound, decoding, azimuthal, panning, surround, transmission, signals, order, source, limited...
R&D Report 1973-31 : The radiation characteristics of leaky coaxial cables at VHF J.L. Eaton, K.J. Kallaway Some experiments have been carried out to investigate the characteristics of a certain type of leaky coaxial cable. The theoretical background of radiation from such a cable is given and from the experimental results the suitability of this type of cable for broadcasting VHF purposes in the open is discussed.
Topics: cable, coaxial, field, braid, propagation, velocity, attenuation, surface, strength, leaky, wire...
R&D Report 1987-15 : Theoretical and practical aspects of the "Functional Absorber" method of arranging sound absorbing panels. E.W. Taylor Measurements of the absorption of sound by functional absorbers (panels of porous material mounted so that both sides are exposed to the sound field) are described, the absorbers being arranged in a number of different configurations. The effect of increasing the surface density of the absorbing panels without significantly changing their...
Topics: absorption, absorbers, absorber, sound, panels, absorbing, reverberation, coefficient, arrangement,...
R&D Report 1990-08 : A practical study of a vibration isolated room J.A. Fletcher It is common practice within the BBC to support studios and similar rooms on "anti-vibration" mountings (AVMs) in order to provide isolation from structure-borne sound. In practice these constructions do not usually achieve the designed resonant frequency. The isolation achieved is also rather doubtful. The source room of the transmission suite at Kingswood Warren, despite careful supervision of its...
Topics: resonant, vibration, frequency, room, source, floated, isolation, stiffness, amplitude, floor,...
R&D Report 1994-05 : Maximal-length sequence methods: Acoustic measurements in the presence of high levels of extraneous noise. R. Walker The use of the maximal-length sequence method to measure acoustic responses in the presence of high levels of extraneous noise is described. Direct and reliable measurements of time and frequency response functions down to a signal-noise ratio of 0 dB are possible. With modest amounts of signal-averaging, response functions down to S/N ratios of -20 dB...
Topics: measurement, frequency, measurements, impulse, signal, response, noise, sequence, averaging,...
R&D Report 1955-06 : The service area of the temporary television transmitter at Redmoss, Aberdeen. L.F. Tagholm, G.I. Ross, R.S.A. Sandell This report shows that the temporary transmitter at Radmoss, near Aberdeen, provides the city of Aberdeen with a reasonable television service using an effective radiated power of 3 watts. It is shown that the service will, in general, be similar to that expected from the final transmitter at Meldrum.
Topics: transmitter, aberdeen, temporary, redmoss, strength, vision, field, watts, field strength,...
R&D Report 1956-10 : Reception disturbances over North Atlantic paths during the years 1947 to 1954. T.W. Bennington The records of reception conditions over North Atlantic paths which are regularly made at Tatsfield have been examined for the eight years 1947 to 1954, with a view to learning something about the effects of ionospheric disturbances upon reception over these paths. The nature of the long-period and seasonal variations in the incidence of such disturbances has been...
Topics: disturbance, magnetic, reception, disturbed, ionospheric, tatsfield, conditions, disturbances,...
BBC Research and Development Reports
by C.J. White, D.W. Taplin, R.S. Sandell, C.R. East
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R&D Report 1956-15 : The service area of the Divis transmitter. C.J. White, D.W. Taplin, R.S. Sandell, C.R. East This report gives the results of a survey of the service area of the Divis television transmitter. It is shown that the extent of the service area predicted by calculation is largely confirmed and that with the addition of the proposed transmitter at Londonderry a 95% coverage of the population of Northern Ireland should be attained.
Topics: divis, transmitter, field, londonderry, sandale, northern, contours, strength, field strength,...
R&D Report 1960-23 : Analogue computer for aerial radiation patterns H. Page, G.J. Phillips, J.A.S. Fox An analogue computer has been constructed to calculate the horizontal radiation patterns of aerial arrays comprising a number of radiating elements mounted on a central support mast. The radiation pattern of a single element must be known, and from this the pattern for a number of identical elements round the mast may be calculated. The currents in the elements may have any desired...
Topics: radiation, uniselector, circuit, wiper, elements, pattern, output, contacts, stepping, wipers,...
R&D Report 1961-01 : A method of assessing the acceptability of stereophonic systems E.R. Wigan In view of the need to compare systems of stereophony, a subjective method of making this comparison has been evolved. The results of a pilot experiment which shows the efficacy of this method are described in this report.
Topics: percival, subjects, spreader, stereophonic, systems, loudspeaker, inexperienced, stereophoner,...
R&D Report 1956-01 : The Philips moving-coil microphone Type EL.6040. W.I. Manson Laboratory tests have been carried out on two specimens of the Philips microphone type EL.6040. Measurements of frequency response, sensitivity, impedance and interference from magnetic fields have been made. The microphone has also been tested in the parabolic reflector PRB/2.
Topics: microphone, frequency, ohms, response, ohm, impedance, specimen, output, parabolic, philips,...
R&D Report 1961-10 : Operational research on studio techniques in stereophony D.E.L. Shorter A series of operational experiments, extending over a period of two and a half years, has been carried out in collaboration with O and M Department (Sound Broadcasting) and the programme departments in order to gain practical experience in stereophony as applied to broadcast programmes. The conclusions to be drawn from the experiments are discussed with particular reference to the problem of...
Topics: stereophonic, microphones, microphone, signals, reverberation, signal, studio, monophonic,...
R&D Report 1964-65 : Field-store converter using ultrasonic delays as the storage medium W. Wharton, E.R. Rout, R.E. Davies In this report, the conversion of television pictures between standards having different field frequencies is discussed and a method is proposed whereby a standards converter capable of conversion between the British 625-line/50 fields and American 525-line/60 fields standards could be realised by the use of ultrasonic delays. Such a standards converter would have a...
Topics: delay, input, output, conversion, converter, fields, lines, field, interpolator, duration, output...
R&D Report 1966-73 : Pulse sound: A system of television sound broadcasting using pulses in the video waveform J.R. Sanders A method of including the sound signal within the video waveform is described which has the advantage that a separate sound transmitter is no longer required; the elimination of the sound transmitter allows the full bandwidth of any radio-frequency channel to be used by the vision transmission. The performance of such a system is shown to be adequate, both in its...
Topics: pulse, pulses, sound, audio, signal, decoder, frequency, waveform, modulation, ratio, spurious...
R&D Report 1964-30 : Measurement of re-radiation from lattice masts at VHF P.C.J. Hill The re-radiation coefficient of a lattice mast which is more than a small fraction of a wavelength wide cannot be calculated theoretically without making assumptions which may not be entirely valid. Re-radiation coefficients of lattice masts have therefore been measured with models, for both vertical and horizontal polarization and the full range of mast sizes likely to be encountered at v.h.f. The...
Topics: mast, lattice, cylinder, cylinders, source, vertical, masts, coefficient, width, polarization, mast...
R&D Report 1962-25 : Effects of polarization on a medium-frequency sky-wave sertvice at low latitudes. G.J. Phillips This is a report on the effects of polarization on a medium-frequency sky-wave service at low latitudes.
Topics: polarization, reflexion, wave, field, polarized, ordinary, ellipse, magnetic, propagation,...
R&D Report 1969-30 : The contrast law of shadow mask display tubes J.R. Sanders, G.D. Judd Contrast law (gamma) measurements on typical 19 inch (49 cm) tubes are discussed. The value of gamma obtained depends on factors such as first-anode potential, and whether cathode or grid drive is used. In addition, any failure of regulation of tube supplies, video non-linearity or clamp failure, can affect the overall gamma of pictures from different types of monitor or receiver using a particular...
Topics: contrast, law, gamma, patch, drive, potentials, grid, measurements, tube, output, department...
R&D Report 1969-29 : A technical appraisal of colour film in television C.B.B. Wood It may seem obvious that, when two imperfect reproduction media are taken in cascade, the end result will probably be inferior to either of them taken singly. It is certainly true that when colour television has for its input material a reproduction of the original scene by means of a colour motion-picture film, the picture quality reaching the television viewer is inferior to that which reaches him when a...
Topics: telecine, colour, film, negative, noise, linearity, scene, television, decibels, luminance, colour...
R&D Report 1971-23 : Colour film telerecording using a shadow-mask display tube J.D. Lunn The development of shadow-mask tubes with increased luminance has justified an investigation into the feasibility of using such a display in colour-film telerecording equipment. This would represent a considerable simplification over an earlier colour telerecording proposal in which a system of dichroic mirrors superimposed the displays from three separate cathode ray tubes, each carrying a single...
Topics: phosphor, display, luminance, telerecording, matrix, spectral, phosphors, film, colour, luminances,...
R&D Report 1977-27 : Digital television: the use of waveform estimates in error correction. C.K.P. Clarke A range of error protection methods for pcm signals is described in which redundancy inherent in the signals is used as an alternative to parity digits. Several ways of synthesising digital filters suitable for use in the protection methods are described. It is expected that, in certain circumstances, a high level of error protection could be obtained without the need for parity digits.
Topics: error, parity, estimates, estimator, signal, correction, characteristic, errors, estimators,...
R&D Report 1977-21 : Digital video: multiple sub-Nyquist coding. J.H. Stott, G.J. Phillips This Report considers the effect of multiple digital coding of signals, with particular emphasis on sub-Nyquist sampling. Theory is developed which shows that conditions exist whereby no extra degradation due to re-sampling occurs. Experimental work confirming these results is described, and the theory is extended to the use of mixed analogue and digital transmissions, including allowance for...
Topics: filter, sampling, comb, analogue, frequency, coding, digital, response, filters, signal, video...
R&D Report 1976-34 : A wide-deviation FM receiver. D.E. Susans The report describes two, simple, wide-deviation FM receivers, one operating in the frequency range 40 MHz to 50 MHz, the other in the range 88 MHz to 100 MHz. The receivers are intended for use with an FM system similar to that of the existing VHF FM service service, but with four times the peak frequency-deviation; they are intended for use in future work on the comparison of different modulation systems. A brief specification...
Topics: khz, receiver, mhz, tuner, amplifier, bbc, band, stereo, frequency, input, tuner unit, input...
R&D Report 1977-02 : Quadraphony: developments in Matrix H decoding. P.S. Gaskell, P.A. Ratliff The Matrix H 2-channel quadraphonic encoding system has been designed to transmit the maximum amount of directional information consistent with mono and stereo compatibility. This report discusses methods of decoding such transmission signals for 'surround-sound' reproduction. The basic form of decoder is a complex-coefficient linear matrix, but this has an inherent lack of separation between the...
Topics: matrix, logic, decoder, decoding, modified, separation, linear, signals, quadraphonic, basic, basic...
R&D Report 1982-08 : The design of a new wideband modular sound absorber. R. Walker, P.H.C. Legate The use is discussed of a modular system of acoustic treatment for use in a wide range of types of studios, control rooms and other areas in which the control of the acoustic environment is essential. Although the system at present in use is generally satisfactory, several defects are identified. The design of a new module intended to absorb sound over the entire audio frequency range and to...
Topics: absorption, frequency, acoustic, modules, coefficient, absorber, module, mineral, panel, resonant,...
R&D Report 1972-02 : Field-store standards conversion: colour operation of the MK 2B (C06/508) converter/synchroniser D.W. Stebbings The report describes the way in which colour television signals are transcoded as part of the standards conversion process. The impairments of colour performance brought about by the standards conversion process are also described, together with methods used to minimise their effects. Transcoding is not used when the equipment is working as a field-store...
Topics: signal, colour, chrominance, signals, delay, luminance, standards, output, subcarrier, burst,...
R&D Report 1986-10 : Development of Slide File -- a digital store for TV stills. M. Weston Slide File is designed to take the place of slide scanners in studios as the prime source of broadcast captions and still pictures. It stores still pictures in electronic digital form and enables them to be selected for transmission by a simple 'cut' or crossfade operation. Such a store provides a convenient means of handling still pictures generated using new electronic techniques as well as handling...
Topics: data, disc, store, pictures, stills, digital, picture, control, computer, input, small pictures,...
R&D Report 1990-15 : The design and application of modular, acoustic diffusing elements. R. Walker The requirements for and the advantages of a modular acoustic diffusing element are described. This module was intended to complement the existing range of acoustic absorbing elements already in widespread use. The theoretical background to the principles is summarised, based on the published work of M.R. Schroeder, and a design for such a module is discussed. The performance of the resulting...
Topics: acoustic, diffusers, bbc, primitive, frequency, modular, diffusing, sequence, module, diffuser,...
R&D Report 1996-10 : Radio with Pictures - A new medium R.H.Evans The advent of digital radio broadcasting provides the broadcaster with the opportunity to convey a variety of data types, to considerably enhance a basic audio service. Analogue FM broadcasts already benefit from a variety of features from the Radio Data System (RDS), but while RDS uses an additional carrier to convey this digital data, the emerging all-digital services such as Eureka DAB, Inmarsat IDDS and WorldSpace, have...
Topics: rwp, audio, pictures, programme, news, data, inmarsat, picture, receiver, radio, television news,...
R&D Report 1960-03 : The power gain of multi-tiered VHF transmitters aerials P. Knight, G.D. Monteath Transmitting aerials for vhf broadcasting usually consist of a number of similar groups or tiers of radiating elements, spaced at intervals along a supporting mast. The power gain of such an arrangement depends on the number of tiers, on the spacing between them, and also on the vertical radiation pattern of each individual tier. A method of calculating the gain is described in this report....
Topics: ooooo, ooo, oooooo, mmmmm, oooo, cfl, iiiii, gain, ooooo ooooo, tfl, moooo ooooo, power radiated,...
R&D Report 1973-04 : Transmission filters for UHF relay stations G.H. Millard Some designs of filter are reviewed and one particular type suitable for use at UHF relay stations is considered in more detail.
Topics: resonators, resonator, mhz, filter, frequency, bbc, impedance, attenuation, filters, coupling,...
R&D Report 1977-37 : Improvements to cheap loudspeakers H.D. Harwood, R. Matthews The sound quality of portable domestic audio equipment is limited mainly by the loudspeaker and cabinet. An investigation has been made to determine whether, at negligible extra cost, worthwhile improvements can be made. It is concluded that in some cases, small but worthwhile improvements are possible.
Topics: unit, loudspeaker, type, elliptical, khz, sound, bare, cone, treated, damping, circular unit, cheap...
R&D Report 1980-04 : Enhanced UK Teletext moves towards still pictures. J.P.Chambers The UK teletext specification includes several provisions for future enhancement of the system while retaining its basic ruggedness and efficiency. By means of an example of a possible specification of an enhanced UK teletext system, this Report draws attention to the immediate benefits that could be provided. It indicates how later extensions up to and including the broadcasting of high-quality still...
Topics: teletext, character, display, characters, row, mode, data, mosaic, codes, control, character codes,...
R&D Report 1992-14 : Building penetration loss measurements for DAB signals at 211 MHz. J.A. Green Digital Audio Broadcasting is being considered as a future method of transmitting radio programmes to the public. Some of the advantages of DAB over conventional Frequency Modulation (FM) include its resistance to multipath and its ruggedness in the presence of interference. Because of these qualities it is ideally suited for reception by mobile and portable receivers. It is proposed that a...
Topics: field, strength, measurements, dab, location, ground, penetration, floor, measured, noise, minimum...
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R&D Report 1956-19 : Low power television transmitters -- Rosemarkie. C.J. White, D.W. Taplin, R.S. Sandell, J. Hall This report gives the results of tests at the site selected for a television transmitter at Rosemarkie, near Inverness. It is shown that a low power transmitter at Rosemarkie will provide most of the population in the Dornoch and Moray Firth areas with a satisfactory television service. Reception tests show that the Meldrum television transmission should provide a...
Topics: aerial, meldrum, rosemarkie, television, strength, site, field, transmitter, dornoch, median,...
R&D Report 1968-09 : U.H.F. Transmitting Aerial for the Sudbury Television Station G.H. Millard A u.h.f. transmitting aerial for the Suffolk area has been built as a top-mast on the new BBC mast at Sudbury. The station started trade tests on 27th January 1968 and full service on 10th February 1968.
Topics: aerial, bbc, channel, mast, transmitter, transmitters, feeder, radiation, transmitting, etn,...
R&D Report 1979-21 : Local oscillator radiation from television receivers. J. Middleton The local oscillator of a television receiver tuned to channel n can cause interference to a neighbouring receiver tuned to channel n+5. If, in modern receivers, this radiation is significantly lower than that prescribed in British Standard BS 905:1969 consideration could be given to relaxing the planning standards in areas where the problem might arise. This report examines the ways local oscillator...
Topics: receiver, radiation, aerial, oscillator, voltage, receivers, chassis, interference, field, aerials,...
R&D Report 1983-16 : A range of combined error correction and recording channel code schemes M.A. Parker This report describes an error corrections scheme which uses the inherent error detection capability of a channel code as one dimension of the correction process. This reduces the total overheads in terms of hardware and data rate required for correction, allowing the advantages of a channel code whilst minimising the overheads.
Topics: error, errors, burst, correction, code, coding, parity, channel, word, data, correction scheme,...
R&D Report 1993-02 : Digital sound: subjective tests on commentary-quality codecs N.H.C. Gilchrist, A.J. Oxenham Subjective tests have been carried out on five commentary-quality audio codecs on behalf of CCIR Task Group 10/2. All codecs operated at a bit rate of 60 kbit/s per mono signal, and were tested in both mono and stereo configurations. Significant differences in performance were found. All codecs introduced some impairment on the most critical programme items.
Topics: mono, codecs, stereo, grades, audio, tests, bbc, codec, material, digital, khz sampling, department...